10-Jan-01 EURONOISE 2001 PATRAS

Time-Series Analysis for Ear-Related and Psychoacoustic Metrics

V. Mellert, H. Remmers, R. Weber, B. Schulte-Fortkamp

10-Jan-01 EURONOISE 2001 PATRAS

how to analyse p(t) to obtain an ear-related parameter?

• general remarks on acoustical analysis• ear-related signal processing• hearing sensation• sensation of vibration• time-frequency representations

10-Jan-01 EURONOISE 2001 PATRAS

acoustical analysis

• time related • level, envelope• statistical level-/ envelope-distributions• modulation-frequency analysis• estimates for impulsive sound

10-Jan-01 EURONOISE 2001 PATRAS

acoustical analysis

• related to spectral properties• weighting functions (A, B, C, ...)• octave, third-octave spectrum• high resolution Fourier – analysis• bandwidth × time-window ≅ 1

10-Jan-01 EURONOISE 2001 PATRAS

ear-related signal processing

• two ears• spatial hearing• source localisation• suppression of

disturbing noise• interaural correlation

Measuring system Head Acoustics

10-Jan-01 EURONOISE 2001 PATRAS

ear-related frequency analysis

excitation at low frequencies

p(t)

Basilar m

embrane

Cochlear

microm

echanics

head diffractionear canalImpedance -transformation

excitation at high frequencies

10-Jan-01 EURONOISE 2001 PATRAS

ear-related frequency analysis

p(t)

Basilar m

embrane

Cochlear

microm

echanics

head diffractionear canalImpedance -transformation

movie from Dept. of Neurophysiology, Univ. of Wisconsin – Madison http://www.neurophys.wisc.edu/h%26b/auditory/animation/animationidx.html

10-Jan-01 EURONOISE 2001 PATRAS

f(t)

Basilar m

embrane

resp. equivalent setof band-pass filters

low frequencies

high frequencies---------

spatial exitationtime dependant

excitationpattern

→ time→location

frequency → location

10-Jan-01 EURONOISE 2001 PATRAS

temporal integration

• nonlinear• loudness 100 – 200 ms• masking effects :

Cited from Zwicker/ Fastl:Psychoacoustics –Facts and Models

10-Jan-01 EURONOISE 2001 PATRAS

frequency (spatial) integration

• loudness: appr. 1/3 octave (bark-scale)• modulation synchrony (object forming, binding problem)

Cited from Zwicker/ Fastl:Psychoacoustics –Facts and Models

10-Jan-01 EURONOISE 2001 PATRAS

loudness summation scheme [Zwicker]

bandpass filters:1/3 ocatave, gam

ma-tone, ftt [Terhardt]

envelopelow passintegrationnon-linearity m

asking properties

sump(t) N(t)

envelopelow passintegrationnon-linearity

10-Jan-01 EURONOISE 2001 PATRAS

hearing sensations

• loudness [Zwicker]• sharpness, sensory

pleasantness [v. Bismark, Aures, Terhardt]

10-Jan-01 EURONOISE 2001 PATRAS

hearing sensations

• roughness [Aures,Terhard, Daniel]

• fluctuation strength [Fastl]

• loudness [Zwicker]• sharpness, sensory

pleasantness [v. Bismark, Aures, Terhardt]

10-Jan-01 EURONOISE 2001 PATRAS

hearing sensations

• roughness [Aures,Terhard, Daniel]

• fluctuation strength [Fastl]

• loudness [Zwicker]• sharpness, sensory

pleasantness [v. Bismark, Aures, Terhardt]

algorithms for measurements partially available

10-Jan-01 EURONOISE 2001 PATRAS

hearing sensations

• roughness [Aures,Terhard, Daniel]

• fluctuation strength [Fastl]

• loudness [Zwicker]• sharpness, sensory

pleasantness [v. Bismark, Aures, Terhardt]

algorithms for measurements partially available

Comprehensive model of the functionality of the ear:„effective“ signal processing [Dau, Kollmeier]

10-Jan-01 EURONOISE 2001 PATRAS

sensation of vibration: thresholds

140 dB ≈ 1 g

10-Jan-01 EURONOISE 2001 PATRAS

threshold measurements: z

10-Jan-01 EURONOISE 2001 PATRAS

threshold measurements: y

10-Jan-01 EURONOISE 2001 PATRAS

vibration total value after ISO 2631-1/2

[ ] nanazW

nkz

nayW

nky

naxW

nkxV akakaka

1

,,, ++=

10-Jan-01 EURONOISE 2001 PATRAS

vibration total value after ISO 2631-1/2

[ ] nanazW

nkz

nayW

nky

naxW

nkxV akakaka

1

,,, ++=

spatial weights

e.g. 0, ..., 1

10-Jan-01 EURONOISE 2001 PATRAS

vibration total value after ISO 2631-1/2

[ ] nanazW

nkz

nayW

nky

naxW

nkxV akakaka

1

,,, ++=

frequency weighted vibration rms-values for x, y, z direction

10-Jan-01 EURONOISE 2001 PATRAS

vibration total value after ISO 2631-1/2

[ ] nanazW

nkz

nayW

nky

naxW

nkxV akakaka

1

,,, ++=

21

0

2//, ))((1

= ∫

T

ySxyxW dttaT

a

21

0

2, ))((1

= ∫

T

SzzW dttaT

a

10-Jan-01 EURONOISE 2001 PATRAS

Just-noticable vibration difference value

10-Jan-01 EURONOISE 2001 PATRAS

multispectrum

• frequency resolution 1/3 octave, except for frequencies below 200 Hz

• time resolution, signal duration• loudness fluctuation: > 1 s• stationary: at least 200 ms• fluctuation strength: time window < 50 ms• roughness: time window < 5 ms

10-Jan-01 EURONOISE 2001 PATRAS

0 29 58 87 116 145 17416-80

100-160

200-250

315

400

500

630

800

1k

1.25k

1.6k

2k

2.5k

3.15k

4k

5k

time [ms]

freq

uenc

y [H

z]

0.0-2.5 2.5-5.0 5.0-7.5 7.5-10.0 10.0-12.5 12.5-15.0 15.0-17.5 17.5-20.0

interior noise of a passenger jetseat #4, 200 ms length, relative level in steps of 2.5 dB

10-Jan-01 EURONOISE 2001 PATRAS

0 29 58 87 116 145 17416-80

100-160

200-250

315

400

500

630

800

1k

1.25k

1.6k

2k

2.5k

3.15k

4k

5k

time [ms]

freq

uenc

y [H

z]

0.0-2.5 2.5-5.0 5.0-7.5 7.5-10.0 10.0-12.5 12.5-15.0 15.0-17.5 17.5-20.0

interior noise of a passenger jetseat #5, 200 ms length, relative level in steps of 2.5 dB

10-Jan-01 EURONOISE 2001 PATRAS

technical multispectrum

• linear transformations (log. amplitude)• seven 1/3 octaves below 80 Hz• three 1/3 octaves from 100 to 160 Hz• two 1/3 octaves from 200 to 250 Hz• additional „tracks“ of weighted vibration signal• time window 6 ms• signal duration 200 ms

10-Jan-01 EURONOISE 2001 PATRAS

towards an ear-related representation

• keeping time – frequency resolution• including masking effects (loudness meter)• object binding (identification of tonal

components)

10-Jan-01 EURONOISE 2001 PATRAS

part-tone time-pattern pttp[Terhardt, Heinbach, Mummert, 1985 – 1998]

time dependantexcitation

pattern

→ time→location

→ time

frequency←

contour-plot:line-pattern of significant features

10-Jan-01 EURONOISE 2001 PATRAS

• 4th order Fourier-time-transformation FTT [Terhardt] (gamma-tone, wavelet)

• identifiy local maxima (level 3 dB) in cuts parallel to frequency axis

• identify local changes in level with respect to time in cuts parallel to time axis

• connect identified points to lines according to threshold criteria

• Ommit short lines (texture) and keep „long“ ones (contour)

10-Jan-01 EURONOISE 2001 PATRAS

pttp-contour of a tyre noise

10-Jan-01 EURONOISE 2001 PATRAS

high-resolution pttp-contour of a helicopter in flight

10-Jan-01 EURONOISE 2001 PATRAS

multispectrum of a helicopter in flight

0 29 58 87 116 145 17416-80

100-160

200-250

315

400

500

630

800

1k

1.25k

1.6k

2k

2.5k

3.15k

4k

5k

time [ms]

freq

uenc

y [H

z]

0.0-2.5 2.5-5.0 5.0-7.5 7.5-10.0 10.0-12.5 12.5-15.0 15.0-17.5 17.5-20.0

10-Jan-01 EURONOISE 2001 PATRAS

technical realisation/ measurements

• no spatial information: mono microphone• acceleration in z sufficient (sensitivity)• single value for vibration in multispectrum• 200 ms time history (steady state)• time window for spectrum > 5 ms• no masking

10-Jan-01 EURONOISE 2001 PATRAS

summary and future developement• time-frequency representations are similar to the

excitation pattern of the ear• data reduction schemes like pttp can improve the

multispectrum representation• additional spectral analysis of the envelope

provides effective information about time fluctuations

• the images are an efficient input for pattern recognition schemes (like ANN)